Flashcards in Inflammatory skin diseases, skin tumours and the eye Deck (54):
Which infections can cause inflammation of the cornea and conjunctiva?
Herpes varicella zoster of trigeminal nerve
Chlamydia (2 forms)
- Trachoma: tropical disease. Common cause of blindness
- Mild disease due to Chlamydia types d-k, aquired during birth from infection in genital tract
What are the causes of cataracts?
What are the causitive agents in retina infections?
Toxoplasma: Cat is host and oocyst in faeces.
- Congenital infection cause severe bilateral disease.
- Acquired causes focal inflammatory disease.
Toxocara canis: from infected dog faeces, larva may migrate to retina and die causing localised inflammation.
What are the possible causes of retinal vascular disease?
- embolis of retinal artery.
- Can look for changes using ophthalmoscope
- flame shaped haemorrhages and exudates
- dot and blot haemorrhages and exudates
What is macular degeneration?
Damage to macule, the central part of vision
What are the two forms of macular degeneration?
1] Dry macular degeneration [age related]
- 90% cases
- Affects >60years old
- progressive visual impairment
- no treatment
2] Wet macular degeneration
- due to new vessel growth beneath retina
- treat with drugs and lasers
- drugs inhibit vessel growth injected directly into the eye.
What is retinoblastoma?
Rare. 10% familial. Genetics, deletion of long arm chromosome 13, loss of RB gene.
Tumour occurs in retina. Treat with enucleation and DXT
How does melanoma arise in the eye?
Arise melanocytes of Uveal tract [Iris, ciliary body or choroid].
2 types on genetic profiling
- type 1 , good prognosis
- type 2; poor prognosis.
Treat with radiotherapy and surgery.
Which common viral infections cause inflammatory skin diseases?
- warts, condylomas
- 1 cold sores
- 2 genital herpes
Herpes Varicella zoster
What are the three stages of dermatitis (eczema)?
- skin red
- weeping serous exudate +/- small vesicles.
- skin is red
- less exudate
- itching ++, crusting.
- skin thick and leathery
- secondary to scratching.
What is seen on microscopy in eczema?
- intercellular oedema within epidermis
- predominantly superficial dermis.
- hyperkeratosis - mild in acute dermatitis, marked in chronic dermatitis.
What is atopic eczema?
Usually starts in childhood, occasionally adults. Often family history. Often associated with asthma and hay fever.
Type 1 hypersensitivity reaction to allergen.
What is contact irritant dermatitis?
Contact irritant dermatitis
- direct injury to skin by irritant, eg acid, alkali, strong detergent, etc
Contact allergic dermatitis
- nickel, dyes, rubber
- act as haptens which combine with epidermal protein to become immunogenic.
What are the other forms of dermatitis?
- affect areas rich in sebaceous glands
- scalp, forehead, upper chest.
- coin shaped lesions.
What are the features of psoriasis?
Well defined, red oval plaques on extensor surfaces
- knees, elbows, sacrum
- fine silvery scale.
Removal of scale causes small bleeding points.
+/- pitting nails.
+/- sero-negative arthritis.
1-2% of the population
What is seen on microscopy in psoriasis?
"Psoriasiform hyperplasia" - distinct appearance:
Regular elongated club shaped rete ridges
Thinning of epidermis over dermal papillae.
Parakeratotic (contain nuclei) scale.
Collections of neutrophils in scale (Munro microabscesses)
What is the pathogenesis of psoriasis?
Clinical and microscopic features reflect massive cell turnover
What is the aetiology of psoriasis?
- Some have family history. - Multiple loci [PSORS] in region of major histocompatibility complex on Chromosome 6p2 implicated
- Same area involved in other autoimmune disorders eg IBD,MS
Environmental trigger factors
Which comorbidities are associated with psoriasis?
- 5-10% associated
- 2-3x risk
- increased risk Non-melanoma skin cancer [eg BCC]
- ? Disease or treatment effect.
What is lupus erythematosus?
- skin only
Systemic LE (SLE)
- visceral disease
+/- involves skin.
- red scaly patches on sun-exposed skin
- scalp involvement causes alopecia.
- Butterfly rash on cheeks and nose.
Auto-immune disorder primarily affecting connective tissues of the body [CT disorder].
- Auto antibodies directed at various tissues.
May affect any part of the body, but importantly kidneys
What is seen microscopically in SLE?
Thin atrophic epidermis. - Inflammation and destruction of adnexal structures.
- LE band
- IgG deposited in basement membrane.
What is dermatomyositis?
Peri-ocular oedema and erythema
- Heliotropic rash
Erythema in photosensitive distribution
- proximal muscle weakness
- can check for creatinine kinase
In adults 25% associated with underlying visceral cancer.
What is seen on microscopy in dermomyositis?
Similar to L.E.
Often a lot of dermal mucin.
What are bullous diseases?
Formation of fluid-filled blisters
What is bullous phemigus diseases?
Group of disorders characterised by loss of cohesion between keratinocytes resulting in an intraepidermal blister.
All types cause fragile blisters/bullae which rupture easily.
Can be extensive +/- involve mucous membranes.
What is the pathogenesis of bullous phemigus diseases?
Autoantibodies, directed against intercellular material.
What is bullous phemigoid disease?
Disease characterised by subepidermal blisters:
Elderly with large tense bullae which do not rupture easily.
Can be localised or extensive disease.
- Autoantibodies to glycoprotein in basement membrane. Can be detected by IMF.
What is dermatitis herpetiformis?
Small intensely itchy blisters. Extensor surfaces
Often young patients. Associated with Coeliac disease.
IgA deposition in dermal papillae on IMF.
- Neutrophil microabscesses in dermal papillae.
Which skin lesions are can be sign of systemic disease?
Dermatomyositis and visceral cancer
Dermatitis herpetiformis and Coeliac disease
Acanthosis Nigricans [ dark warty lesions in armpits] and internal malignancy.
Necrobiosis Lipoidica [red + yellow plaque on legs] and Diabetes Mellitus
Erythema Nodosum [red tender nodules on shins] associated with infections elsewhere esp.lung, drugs, and other diseases
Which skin lesions are caused by metabolic disorders?
Xanthoma’s [yellow plaques often eyelids] and hyperlipaemis’s
Porphyria. Group of disorders caused by defective synthesis of haem, part of haemoglobin
Symptoms vary depending on type [abdo.pains, psychiatric disturbance ,skin lesions]
What is porphyria cutanea tarda (PCT)?
Commonest type. 20% inherited, A.D., 80% acquired [hepatitisC]. Alcohol can precipitate.
- uroporphyrinogen decarboxylase deficiency (UROD)
- leads to build up of porphyrin compounds in the skin
- these cause tissue damage when exposed to sunlight.
Causes Blisters and scarring of skin
Diagnosis, can look for porphyrins is urine [goes dark on light exposure].
What is basal cell carcinoma (BCC)?
Commonest malignant tumour
- Metastases very rare.
- Sun exposed site, especially face
- Occasional secondary to radiotherapy
- Pale skin that burns easily
Rare - Gorlin’s syndrome
What is the clinical presentation of BCC?
Late: ulcer (rodent ulcer).
Morphoeic BCC - ill defined and infiltrative.
What are the microscopic features of BCC?
Tumour composed of islands of basaloid cells with peripheral palisade
What is squamous call carcinoma?
- Usually occurs in sun exposed sites.
- Increased risk in tropical countries.
- tars, mineral oils, soot.
- Percival Pott noted SCC scrotum in chimney sweeps.
- SCC arises within these (Marjolins ulcer).
- renal transplant patients at increased risk.
Drugs, some newer drugs for melanoma
What is the clinical presentation of SCC?
Nodule with ulcerated, crusted surface
What is the microscopic appearance of SCC?
Invasive islands and trabeculae of squamous cells showing cytological atypia.
How common are metastases in SCC?
5% (lip, ear, perineum)
What are the other high risk features of SCC?
> 2 cm, >4mm thick, high grade
What is actinic keratosis?
Pre-malignant disease; actinic [solar]keratosis.
Dysplasia to Squamous epithelium.
Very common on chronic sun exposed sites.
Scaly lesion with erythematous base
Only rarely progresses to invasive disease.
May spontaneously resolve
What are melanocytes?
Melanocytes derive from neural crest
Function; to form melanin which is transferred to epidermal cells to protect the nucleus from UV radiation.
Give rise to tumours
- Benign; naevi [moles]
- Malignant; Melanoma
What are melanocytic naevi?
Local benign collections of melanocytes
What are the two types of naevi?
Superficial; congenital or acquired
Deep; Blue naevi.[ mongolion spot]
What is dysplastic naevus syndrome?
Families with increased incidence of melanoma
Multiple clinically atypical moles
Increased risk of developing melanoma.
What are the features of melanoma?
Much rarer than BCC and SCC.
Incidence is rising rapidly.
Very dangerous malignancy which can metastasize widely.
How can you tell the difference between a naevi and a melanoma?
What are the main risk factors for melanoma?
- especially short intermittent severe exposure
- Celtic with red hair, blue eyes, fair complexions who tan poorly most at risk.
- Melanoma rare in dark skinned people.
- Dysplastic naevus syndrome
- multiple large atypical moles
Giant congenital naevi
- small risk (10%) turn malignant.
What is lentigo maligna?
Face, elderly people. Slow growing, flat, pigmented patch.
Micro: Proliferation of atypical melanocytes along basal layer of epidermis. Skin also shows signs of chronic sun damage.
Late in disease, melanocytes may invade dermis (lentigo maligna melanoma) with potential to metastasise.
What is acral lentigenous melanoma?
Palms and soles, occasionally subungual.
Commonest form in afro-caribbeans. Forms enlarging pigmented patch.
Micro: Similar to lentigo maligna except no marked sun damage.
What is superficial spreading melanoma?
Commonest type in Britain.
Early: flat macule. Late: blue/black nodule.
Micro: Proliferation of atypical melanocytes which invade epidermis [pagetoid spread] and dermis.
Genetics; Often BRAF mutations ? Possible target for anticancer agents.
What is nodular melanoma?
Starts as pigmented nodule. +/- ulceration. Poor prognosis.
Micro: Invasive atypical melanocytes invade dermis to produce nodules of tumour cells.
What is Breslow thickness?
Predicts 5 year prognosis
Measure on microscope from granular layer of epidermis to base of tumour
4 = 45-60%
% = 5 year survival
Aside from Breslow, what are the other prognostic factors in
Site - BANS - back, arms (posterior upper), neck, scalp. All poorer prognosis
Sentinel Node. Lymph node which drains from melanoma first. Good indicator of prognosis. Removed and if positive, rest of lymph nodes in that anatomic area removed to try and halt disease progression.